An electrical connector assembly, for instance to connect a cable to a proximity switch such as described in copending patent application Ser. No. 07/854,411 filed Mar. 19, 1992 (now U.S. Pat. No. 5,209,669), has a threaded part having a conductor, an unthreaded part normally mounted on a cable, and a nut on the unthreaded part. This unthreaded part has a conductor, is fittable along an axis with the threaded part for engagement of the conductors with each other, and is formed with front and back axially spaced stops. The nut is axially displaceable on the unthreaded part between the stops through a predetermined axial distance, is rotatable about the axis on the unthreaded part, and is threadedly engageable with the threaded part to lock the parts axially together with the nut engaging the front stop. Thus to make the electrical connection the two parts are fitted together to engage their conductors with each other, and then the nut is screwed down to prevent them from pulling axially apart.
This system can loosen by unscrewing of the nut when it is vibrated. Accordingly German patent document 2,136,500 filed Jul. 21, 1971 by G. Spinner et al provides axially projecting teeth on the front end of the nut and on the threaded part an axially displaceable ring that is formed with axially projecting teeth and that also is prevented from rotating on the threaded part. Thus this ring is retracted against the force of a spring as the nut is screwed down, then is released so the spring presses its teeth into the teeth of the nut, preventing same from rotating. Such a system is expensive to manufacture due to the provision of several extra moving parts and is somewhat cumbersome to use.
German patent document 2,840,728 filed Sep. 19, 1978 by G. Spinner proposes a similar system where the axially displaceable toothed ring is carried on the nut, and the threaded part is itself unitarily formed with a ring of sawtooth-shaped teeth engageable with the teeth of the ring. This arrangement is merely a kinematic rearrangement of the parts of the other above-described system giving no significant advantages.
In German patent 3,209,734 filed Mar. 17, 1982 by A. Stieler the separate axially movable ring is dispensed with, and instead the threaded part is provided with one or more axially projecting but also axially deflectable teeth. While this does cut down on the complexity of the parts somewhat, it still is a fairly complicated structure.
German patent 3,625,134 filed Jul. 25, 1986 proposes such a system where the teeth are radially deflectable, but must be ratcheted during the entire axial travel of the nut. Furthermore its structure is fairly complex.
In U.S. Pat. No. 4,239,314 of Anderson et al a fairly complex arrangement is provided to retain the two parts together. The teeth ratchet during the entire movement of the nut, and the device is, however, fairly complicated and expensive to build.